diff --git a/ddl/column_test.go b/ddl/column_test.go
index 4df68425f0eb2..b80933ddbcaf3 100644
--- a/ddl/column_test.go
+++ b/ddl/column_test.go
@@ -191,7 +191,7 @@ func TestColumnBasic(t *testing.T) {
 
 	require.Nil(t, table.FindCol(tbl.Cols(), "c4"))
 
-	jobID := testCreateColumn(tk, t, testNewContext(store), tableID, "c4", "after c3", 100, dom)
+	jobID := testCreateColumn(tk, t, testkit.NewTestKit(t, store).Session(), tableID, "c4", "after c3", 100, dom)
 	testCheckJobDone(t, store, jobID, true)
 
 	tbl = testGetTable(t, dom, tableID)
@@ -221,7 +221,7 @@ func TestColumnBasic(t *testing.T) {
 	require.Len(t, values, 4)
 	require.Equal(t, values[3].GetInt64(), int64(14))
 
-	jobID = testDropColumnInternal(tk, t, testNewContext(store), tableID, "c4", false, dom)
+	jobID = testDropColumnInternal(tk, t, testkit.NewTestKit(t, store).Session(), tableID, "c4", false, dom)
 	testCheckJobDone(t, store, jobID, false)
 
 	tbl = testGetTable(t, dom, tableID)
@@ -231,7 +231,7 @@ func TestColumnBasic(t *testing.T) {
 	require.Len(t, values, 3)
 	require.Equal(t, values[2].GetInt64(), int64(13))
 
-	jobID = testCreateColumn(tk, t, testNewContext(store), tableID, "c4", "", 111, dom)
+	jobID = testCreateColumn(tk, t, testkit.NewTestKit(t, store).Session(), tableID, "c4", "", 111, dom)
 	testCheckJobDone(t, store, jobID, true)
 
 	tbl = testGetTable(t, dom, tableID)
@@ -241,7 +241,7 @@ func TestColumnBasic(t *testing.T) {
 	require.Len(t, values, 4)
 	require.Equal(t, values[3].GetInt64(), int64(111))
 
-	jobID = testCreateColumn(tk, t, testNewContext(store), tableID, "c5", "", 101, dom)
+	jobID = testCreateColumn(tk, t, testkit.NewTestKit(t, store).Session(), tableID, "c5", "", 101, dom)
 	testCheckJobDone(t, store, jobID, true)
 
 	tbl = testGetTable(t, dom, tableID)
@@ -251,7 +251,7 @@ func TestColumnBasic(t *testing.T) {
 	require.Len(t, values, 5)
 	require.Equal(t, values[4].GetInt64(), int64(101))
 
-	jobID = testCreateColumn(tk, t, testNewContext(store), tableID, "c6", "first", 202, dom)
+	jobID = testCreateColumn(tk, t, testkit.NewTestKit(t, store).Session(), tableID, "c6", "first", 202, dom)
 	testCheckJobDone(t, store, jobID, true)
 
 	tbl = testGetTable(t, dom, tableID)
@@ -277,7 +277,7 @@ func TestColumnBasic(t *testing.T) {
 	require.Equal(t, values[0].GetInt64(), int64(202))
 	require.Equal(t, values[5].GetInt64(), int64(101))
 
-	jobID = testDropColumnInternal(tk, t, testNewContext(store), tableID, "c2", false, dom)
+	jobID = testDropColumnInternal(tk, t, testkit.NewTestKit(t, store).Session(), tableID, "c2", false, dom)
 	testCheckJobDone(t, store, jobID, false)
 
 	tbl = testGetTable(t, dom, tableID)
@@ -288,22 +288,22 @@ func TestColumnBasic(t *testing.T) {
 	require.Equal(t, values[0].GetInt64(), int64(202))
 	require.Equal(t, values[4].GetInt64(), int64(101))
 
-	jobID = testDropColumnInternal(tk, t, testNewContext(store), tableID, "c1", false, dom)
+	jobID = testDropColumnInternal(tk, t, testkit.NewTestKit(t, store).Session(), tableID, "c1", false, dom)
 	testCheckJobDone(t, store, jobID, false)
 
-	jobID = testDropColumnInternal(tk, t, testNewContext(store), tableID, "c3", false, dom)
+	jobID = testDropColumnInternal(tk, t, testkit.NewTestKit(t, store).Session(), tableID, "c3", false, dom)
 	testCheckJobDone(t, store, jobID, false)
 
-	jobID = testDropColumnInternal(tk, t, testNewContext(store), tableID, "c4", false, dom)
+	jobID = testDropColumnInternal(tk, t, testkit.NewTestKit(t, store).Session(), tableID, "c4", false, dom)
 	testCheckJobDone(t, store, jobID, false)
 
-	jobID = testCreateIndex(tk, t, testNewContext(store), tableID, false, "c5_idx", "c5", dom)
+	jobID = testCreateIndex(tk, t, testkit.NewTestKit(t, store).Session(), tableID, false, "c5_idx", "c5", dom)
 	testCheckJobDone(t, store, jobID, true)
 
-	jobID = testDropColumnInternal(tk, t, testNewContext(store), tableID, "c5", false, dom)
+	jobID = testDropColumnInternal(tk, t, testkit.NewTestKit(t, store).Session(), tableID, "c5", false, dom)
 	testCheckJobDone(t, store, jobID, false)
 
-	jobID = testDropColumnInternal(tk, t, testNewContext(store), tableID, "c6", true, dom)
+	jobID = testDropColumnInternal(tk, t, testkit.NewTestKit(t, store).Session(), tableID, "c6", true, dom)
 	testCheckJobDone(t, store, jobID, false)
 
 	testDropTable(tk, t, "test", "t1", dom)
diff --git a/ddl/ddl.go b/ddl/ddl.go
index 69f6fe2323255..f7c77a90b6463 100644
--- a/ddl/ddl.go
+++ b/ddl/ddl.go
@@ -499,11 +499,7 @@ func (d *ddl) Start(ctxPool *pools.ResourcePool) error {
 			asyncNotify(worker.ddlJobCh)
 		}
 
-		err = kv.RunInNewTxn(d.ctx, d.store, true, func(ctx context.Context, txn kv.Transaction) error {
-			t := meta.NewMeta(txn)
-			d.ddlSeqNumMu.seqNum, err = t.GetHistoryDDLCount()
-			return err
-		})
+		d.ddlSeqNumMu.seqNum, err = d.GetNextDDLSeqNum()
 		if err != nil {
 			return err
 		}
@@ -526,6 +522,18 @@ func (d *ddl) Start(ctxPool *pools.ResourcePool) error {
 	return nil
 }
 
+// GetNextDDLSeqNum return the next ddl seq num.
+func (d *ddl) GetNextDDLSeqNum() (uint64, error) {
+	var count uint64
+	err := kv.RunInNewTxn(d.ctx, d.store, true, func(ctx context.Context, txn kv.Transaction) error {
+		t := meta.NewMeta(txn)
+		var err error
+		count, err = t.GetHistoryDDLCount()
+		return err
+	})
+	return count, err
+}
+
 func (d *ddl) close() {
 	if isChanClosed(d.ctx.Done()) {
 		return
diff --git a/ddl/fail_test.go b/ddl/fail_test.go
index 741fa739ca289..413aad6172822 100644
--- a/ddl/fail_test.go
+++ b/ddl/fail_test.go
@@ -60,7 +60,7 @@ func TestFailBeforeDecodeArgs(t *testing.T) {
 	}
 	d.SetHook(tc)
 	defaultValue := int64(3)
-	jobID := testCreateColumn(tk, t, testNewContext(store), tableID, "c3", "", defaultValue, dom)
+	jobID := testCreateColumn(tk, t, testkit.NewTestKit(t, store).Session(), tableID, "c3", "", defaultValue, dom)
 	// Make sure the schema state only appears once.
 	require.Equal(t, 1, stateCnt)
 	testCheckJobDone(t, store, jobID, true)
diff --git a/executor/executor.go b/executor/executor.go
index e89517a1a4387..053a24e351be5 100644
--- a/executor/executor.go
+++ b/executor/executor.go
@@ -484,7 +484,7 @@ type ShowDDLJobsExec struct {
 // nolint:structcheck
 type DDLJobRetriever struct {
 	runningJobs    []*model.Job
-	historyJobIter *meta.LastJobIterator
+	historyJobIter meta.LastJobIterator
 	cursor         int
 	is             infoschema.InfoSchema
 	activeRoles    []*auth.RoleIdentity
diff --git a/meta/meta.go b/meta/meta.go
index 830493b0bec47..2fd9b005da9c0 100644
--- a/meta/meta.go
+++ b/meta/meta.go
@@ -1045,23 +1045,28 @@ func (m *Meta) GetLastNHistoryDDLJobs(num int) ([]*model.Job, error) {
 }
 
 // LastJobIterator is the iterator for gets latest history.
-type LastJobIterator struct {
-	iter *structure.ReverseHashIterator
+type LastJobIterator interface {
+	GetLastJobs(num int, jobs []*model.Job) ([]*model.Job, error)
 }
 
 // GetLastHistoryDDLJobsIterator gets latest N history ddl jobs iterator.
-func (m *Meta) GetLastHistoryDDLJobsIterator() (*LastJobIterator, error) {
+func (m *Meta) GetLastHistoryDDLJobsIterator() (LastJobIterator, error) {
 	iter, err := structure.NewHashReverseIter(m.txn, mDDLJobHistoryKey)
 	if err != nil {
 		return nil, err
 	}
-	return &LastJobIterator{
+	return &HLastJobIterator{
 		iter: iter,
 	}, nil
 }
 
+// HLastJobIterator is the iterator for gets the latest history.
+type HLastJobIterator struct {
+	iter *structure.ReverseHashIterator
+}
+
 // GetLastJobs gets last several jobs.
-func (i *LastJobIterator) GetLastJobs(num int, jobs []*model.Job) ([]*model.Job, error) {
+func (i *HLastJobIterator) GetLastJobs(num int, jobs []*model.Job) ([]*model.Job, error) {
 	if len(jobs) < num {
 		jobs = make([]*model.Job, 0, num)
 	}
diff --git a/sessionctx/context.go b/sessionctx/context.go
index 0b4948877aeb1..be3329c1de4d3 100644
--- a/sessionctx/context.go
+++ b/sessionctx/context.go
@@ -20,6 +20,7 @@ import (
 	"time"
 
 	"github.com/pingcap/errors"
+	"github.com/pingcap/kvproto/pkg/kvrpcpb"
 	"github.com/pingcap/tidb/kv"
 	"github.com/pingcap/tidb/metrics"
 	"github.com/pingcap/tidb/parser/model"
@@ -48,7 +49,12 @@ type Context interface {
 	NewTxn(context.Context) error
 	// NewStaleTxnWithStartTS initializes a staleness transaction with the given StartTS.
 	NewStaleTxnWithStartTS(ctx context.Context, startTS uint64) error
-
+	// SetDiskFullOpt set the disk full opt when tikv disk full happened.
+	SetDiskFullOpt(level kvrpcpb.DiskFullOpt)
+	// RollbackTxn rolls back the current transaction.
+	RollbackTxn(ctx context.Context)
+	// CommitTxn commits the current transaction.
+	CommitTxn(ctx context.Context) error
 	// Txn returns the current transaction which is created before executing a statement.
 	// The returned kv.Transaction is not nil, but it maybe pending or invalid.
 	// If the active parameter is true, call this function will wait for the pending txn
diff --git a/util/mock/context.go b/util/mock/context.go
index 54658dc6aa4a8..a0525c3e4ef42 100644
--- a/util/mock/context.go
+++ b/util/mock/context.go
@@ -25,6 +25,7 @@ import (
 	"github.com/pingcap/tidb/kv"
 	"github.com/pingcap/tidb/parser/ast"
 	"github.com/pingcap/tidb/parser/model"
+	"github.com/pingcap/tidb/parser/terror"
 	"github.com/pingcap/tidb/sessionctx"
 	"github.com/pingcap/tidb/sessionctx/variable"
 	"github.com/pingcap/tidb/util"
@@ -247,6 +248,23 @@ func (c *Context) RefreshVars(ctx context.Context) error {
 	return nil
 }
 
+// RollbackTxn indicates an expected call of RollbackTxn.
+func (c *Context) RollbackTxn(ctx context.Context) {
+	defer c.sessionVars.SetInTxn(false)
+	if c.txn.Valid() {
+		terror.Log(c.txn.Rollback())
+	}
+}
+
+// CommitTxn indicates an expected call of CommitTxn.
+func (c *Context) CommitTxn(ctx context.Context) error {
+	defer c.sessionVars.SetInTxn(false)
+	if c.txn.Valid() {
+		return c.txn.Commit(ctx)
+	}
+	return nil
+}
+
 // InitTxnWithStartTS implements the sessionctx.Context interface with startTS.
 func (c *Context) InitTxnWithStartTS(startTS uint64) error {
 	if c.txn.Valid() {